Radar sensors are increasingly being used in motor vehicles for safety-relevant functions. The identification of an elevation angle of a localized object is of increasing importance in this context. For example, information for classifying the object as one that can or cannot be driven over can be obtained from an elevation angle and a distance of a localized object. If the radar sensor is misaligned in an elevation direction, this can negatively affect the reliability with which objects are classified. A determination of a horizontal angle of detected radar objects can, however, also be negatively affected by a radar sensor that is misaligned in an elevation direction, if the antenna diagram of the antennas which is utilized for evaluation deviates from the antenna diagram that is effective in the actual elevation direction.
Patent document DE 10 2011 079 522 A1 discusses a method in which a misalignment angle of the radar sensor in an elevation direction is identified on the basis of the characteristic, dependent on the angular alignment of the radar sensor in an elevation direction, of a ground clutter signal received by the radar sensor.
Patent document DE 199 37 723 C2 discusses a method in which received rays reflected from a radar target are compared with antenna diagrams that are associated with different misalignments at intervals of 0.5°, and a misalignment of the radar sensor is inferred from that comparison. By averaging over the elevation angles stored in many measurement cycles, the erroneous angle most often stored is identified as an angle for an elevation angle misalignment of the radar sensor.
Patent document DE 10 2008 054 579 A1 discusses a method in which a vertical misalignment of a radar sensor is identified on the basis of how well a signal reflected from a radar target matches a sensor profile for the horizontal angle which indicates an aligned radar sensor.